1. Field of Invention
The present invention is directed to the production of pickled vegetable or fruit products. More particularly, the present invention is directed to a method of producing sweet pickled vegetable or fruit products.
2. Description of the Prior Art
The traditional method making sweet pickles is a process known as a tank sweetening. In the tank sweetening method, pickle stock is sweetened by immersion in a series of progressively more concentrated sugar solutions until the concentration of the sugar solids in the pickle is raised to about 40.degree. Brix. In a typical process, pickle stock is first placed in a tank containing a syrup that is 30% sugar by weight. After one day, diffusion has caused the sugar concentration to equalize in the liquid phase and the pickle at about 15% by weight. The liquid phase is then either replaced with a higher concentration syrup or withdrawn, mixed with additional solid sugar to raise the concentration, and then returned to the tank. By a series of step-by-step increases in sugar concentration, the desired 40.degree. Brix sweet pickles can be produced in a period of about 3 to 15 days.
Tank sweetening on a commercial scale has several disadvantages. First, the multi-step increases in sugar concentration requires that a manufacturer employ multiple tanks. Furthermore, the process produces large quantities of excess syrup. Finally, tank sweetening is undesirable because of the numerous sanitary and safety hazards associated with handling the syrup (e.g., contamination and spillage).
It would be extremely desirabe if sweet pickles could be produced by a syrup immersion process that elimnated as many of the syrup increase steps as possible. One of the major problems with trying to produce sweet pickles using a higher concentration sugar syrup is the problem of shrinkage of the pickle stock. The water content of cucumbers, for example, is above 90% by weight. Water migrates from the pickle stock into the surrounding liquid phase much more rapidly than the sugar can migrate across the membrane of the pickle stock. The net effect is that the pickle stock shrinks substantially and irreversibly.
Over the years, several processes as have been developed to try and eliminate this problem. One such process is described in U.S. Pat. No. 2,865,758. In this patent the stock is first punctured and then submerged in the sugar syrup. While the stock is submerged the entire process is subjected to a vacuum pressure and is held for about 15 to 20 minutes. As the vacuum is released, the stock then absorbes the sugar solution.
In U.S. Pat. No. 2,801,925 the stock is subjected to a vacuum at an elevated temperature. Once the vacuum is reached the fruit is flooded within the chamber with the desired sugar solution. After about 15 minutes, the vacuum is broken and the fruit is allowed to stand in the flooding solution at atmospheric pressure and at temperatures which naturally decrease to room temperature for approximately a 24 to 72 hour period.
U.S. Pat. No. 4,402,988 also describes a very similar situation. The process in U.S. Pat. No. 4,402,988 differs somewhat in that it uses a much higher vacuum and allows the dwell time of the stock to be immersed in the sugar solution for only about 10 seconds. Thereafter, they are removed and the product is frozen for further processing.
None of the above mentioned U.S. patents describe or disclose the process for producing a sweet pickle that Applicants have developed.